MULTILAYER FUEL LINE

Abstract

A plastic line including at least an inner layer, which directly or indirectly encloses an interior space, and an outer layer directly adjacent to the inner layer. The inner layer is based on fluoropolymer, and the outer layer consists of the following constituents: (A) 51-98% of a polyamide from the following group: PA 616, PA 516, PA 618 or mixtures thereof, and copolymers containing at least 50% of at least one of these polyamides and also mixtures of at least one of these polyamides with a further different thermoplastic material (A2), wherein the proportion of these polyamides in such mixtures makes up at least 50%; (B) 2-20% of impact modifiers or plasticizers; (C) 0-29% of additives different from (A) and (B), wherein the components (A)-(C) together make up 100% of the material of the outer layer.

Claims

1. A plastics line comprising at least two layers, an internal layer which directly or indirectly encloses an internal space of the line, and an external layer which directly adjoins the internal layer, wherein the structure of the internal layer is based on fluoropolymer, and wherein the external layer consists of the following constituents: (A) 51-98 percent by weight of a polyamide selected from the following group: PA 616, PA 516, PA 618 and mixtures thereof, copolymers comprising at least 50 percent by weight of at least one of these polyamides, or mixtures of at least one of these polyamides with a further thermoplastic (A2) differing therefrom, wherein the proportion of these polyamides in such mixtures is at least 50 percent by weight; (B) 2-20 percent by weight of one of impact modifiers or plasticizers; and (C) 0-29 percent by weight of additives differing from (A) and (B), wherein the proportions by weight of the components (A)-(C) give a total of 100 percent by weight of the material of the external layer.

2. The plastics line as claimed in claim 1, wherein the component (A) consists exclusively of PA 616, or of a copolymer with a proportion of PA 616 of at least 80 percent by weight, or of a mixture of PA 616 with another polyamide, and wherein the proportion of PA 616 is at least 80 percent by weight, based on the mixture of PA 616 with the other polyamide.

3. The plastics line as claimed in claim 1, wherein the external layer delimits the line externally, or wherein outside of the external layer there are one or two further external layers, and the outermost thereof delimits the line externally.

4. The plastics line as claimed in claim 1, wherein the further thermoplastic (A2) of the component (A) is a polyamide differing from PA 616, PA 516, PA 618.

5. The plastics line as claimed in claim 1, wherein the proportion of the component (A) in the material of the external layer is in the range of 80-95 percent by weight, or, if a conductivity additive is used as component (C), the proportion of the component (A) in the material of the external layer is in the range of 55-85 percent by weight.

6. The plastics line as claimed in claim 1, wherein the proportion of the component (B) in the material of the external layer is in the range of 5-18 percent by weight.

7. The plastics line as claimed in claim 1, wherein the material of the external layer comprises not only at least one impact modifier but also at least one plasticizer.

8. The plastics line as claimed in claim 1, wherein the proportion of the component (C) in the material of the external layer is in the range of 0.1-3 percent by weight; or wherein component (C) is selected from at least one added substance from the following group: antioxidants, processing aids, UV stabilizers, heat stabilizers, pigments, masterbatch carriers, conductivity additives, lubricants or mixtures thereof.

9. The plastics line as claimed in claim 1, wherein the structure of the internal layer is based on fluoropolymer based at least on ethylene and tetrafluoroethylene, with or without further blocks selected from the group of: propylene blocks, hexene blocks, or wherein the internal layer consists of the following constituents: (a) 75-100 percent by weight of fluoropolymer based at least on ethylene and tetrafluoroethylene, with or without at least one of hexafluoropropylene blocks and perfluorohexene blocks; and (b) 0-25 percent by weight of additives; wherein the components (a) and (b) give a total of 100 percent by weight of the material of the internal layer.

10. The plastics line as claimed in claim 1, wherein the structure of the internal layer is based on fluoropolymer based at least on ethylene and tetrafluoroethylene, with or without further blocks selected from the group of: propylene blocks, hexene blocks, or wherein the internal layer consists of the following constituents: (a) 75-100 percent by weight of fluoropolymer based at least on ethylene and tetrafluoroethylene, with or without at least one of hexafluoropropylene blocks and perfluorohexene blocks; and (b) 0-25 percent by weight of additives; wherein the components (a) and (b) give a total of 100 percent by weight of the material of the internal layer.

11. The plastics line as claimed in claim 9, wherein component (b) comprises at least one conductivity additive.

12. The plastics line as claimed in claim 1, wherein the thickness of the internal layer is in the range of 0.08-1 mm, or the thickness of the external layer is in the range of 0.5-2 mm, or wherein the total wall thickness of the line is in the range of 0.9-3.0 mm.

13. The plastics line as claimed in claim 1, wherein it consists exclusively of the internal layer and the external layer.

14. The plastics line as claimed in claim 1, wherein the plastics line has been produced in a coextrusion process.

15. The plastics line as claimed in claim 1, in the form of a line which can be configured at least sectionally as corrugated pipe.

16. A process for the production of a fuel line as claimed in claim 1, wherein the two layers are molded in a continuous or batch process, to give a hollow body.

17. The plastics line as claimed in claim 1, wherein the external layer consists of the following constituents: (A) 75-98 percent by weight of a polyamide selected from the following group: PA 616, PA 516, PA 618 and mixtures thereof, copolymers comprising at least 50 percent by weight of at least one of these polyamides, and mixtures of at least one of these polyamides with a further thermoplastic (A2) differing therefrom, wherein the proportion of these polyamides in such mixtures is at least 50 percent by weight; (B) 2-20 percent by weight of at least one of impact modifiers and plasticizers; and (C) 0-5 percent by weight, of additives differing from (A) and (B), wherein the proportions by weight of the components (A)-(C) give a total of 100 percent by weight of the material of the external layer.

18. The plastics line as claimed in claim 1, wherein the external layer delimits the line externally, and the proportion of the component (A) is in the range of 75-98 percent by weight and the proportion of the component (C) is in the range of 0-5 percent by weight, or wherein outside of the external layer there are one or two further external layers, and the outermost thereof delimits the line externally, and the configuration of these further external layers is based on PA 612, PA 6, PA 616 or on a mixture thereof.

19. The plastics line as claimed in claim 1, wherein the further thermoplastic (A2) of the component (A) is a polyamide differing from PA 616, PA 516, PA 618, in the form of an aliphatic or semiaromatic polyamide, selected from the group consisting of: PA 6, PA 612, PA 10T/6T, PA 1212, PA 66, PA 11, PA 106, PA 1012, PA 10T/612, PA 10T/610, PA 9T.

20. The plastics line as claimed in claim 1, wherein the component (A) is free from PA 12, or free from polyamide elastomers, or free not only from PA 12 but also from polyamide elastomers.

21. The plastics line as claimed in claim 1, wherein the proportion of the component (A) in the material of the external layer is in the range of 84-88 percent by weight, or, if a conductivity additive is used as component (C), in the form of carbon black, the proportion of the component (A) in the material of the external layer is in the range of 60-75 percent by weight.

22. The plastics line as claimed in claim 1, wherein the proportion of the component (B) in the material of the external layer is in the range of 10-15 percent by weight.

23. The plastics line as claimed in claim 1, wherein the material of the external layer comprises not only at least one impact modifier but also at least one plasticizer, and wherein the proportion present of the impact modifier is in the range of 2-10 percent by weight, or in the range of 4-8 percent by weight, based on the entire composition of the external layer, and the proportion present of the plasticizer is in the range of 2-12 percent by weight, or in the range of 5-10 percent by weight, based on the entire composition of the external layer.

24. The plastics line as claimed in claim 1, wherein the material of the external layer comprises at least one impact modifier which is an acid-modified ethylene-α-olefin copolymer, including an anhydride-grafted, or maleic-anhydride-grafted, ethylene/α-olefin copolymer, including ethylene/butylene, ethylene/propylene, or ethylene-propylene/ethylene-butylene copolymer thus modified/grafted, or wherein the plasticizer of the external layer is selected as hydroxybenzoic-ester-based or sulfonamide-based plasticizer, including those selected from the class of the N-substituted sulfonamide plasticizers, including BBSA.

25. The plastics line as claimed in claim 1, wherein the proportion of the component (C) in the material of the external layer is in the range of 0.5-1 percent by weight; or wherein the component (C) comprises a heat stabilizer in the form of an organic heat stabilizer, including those based on a phenol, on a phosphonite or on a HALS stabilizer, or wherein the component (C) comprises a conductivity additive, including carbon black, in a proportion in the range of 0.1-27 percent by weight, based on the entire composition of the external layer.

26. The plastics line as claimed in claim 1, wherein the structure of the internal layer is based on fluoropolymer based at least on ethylene and tetrafluoroethylene, with or without further blocks selected from the group of: hexafluoropropylene blocks, perfluorohexene blocks, including those in the form of fluorine-containing ethylenic polymer which has a carbonyl group and which comprise or comprises no amide group, imide group, urethane group or urea group, or wherein the internal layer consists of the following constituents: (a) 85-98 percent by weight, of fluoropolymer based at least on ethylene and tetrafluoroethylene, with or without hexafluoropropylene blocks and/or perfluorohexene blocks, having carbonyl groups; and (b) 0-25 percent by weight of additives, wherein the components (a) and (b) give a total of 100 percent by weight of the material of the internal layer.

27. The plastics line as claimed in claim 9, wherein the component (b) comprises at least one additive for increasing electrical conductivity, including in the form of carbon black particles.

28. The plastics line as claimed in claim 9, wherein the component (b) comprises at least one conductivity additive, in a proportion in the range of 0.1-20 percent by weight, based on the entire composition of the internal layer.

29. The plastics line as claimed in claim 1, wherein the thickness of the internal layer is in the range of 0.1-0.9 mm, or wherein the thickness of the external layer is in the range of 0.6-1.75 mm, or wherein the total wall thickness of the line is in the range of 1.0-2.0 mm.

30. The plastics line as claimed in claim 1, in the form of a line which can be configured at least sectionally as corrugated pipe, as line for internal combustion engines, including in the automobile sector, including lines for fuel, including gasoline, urea or coolant.

31. A process for the production of a fuel line as claimed in claim 16, wherein the two layers are molded in an extrusion blow molding process, a tandem extrusion process, an injection-molding process, an internal-(gas)-pressure injection-molding process, a sheathing process or a (co)extrusion process, to give a hollow body including a line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Preferred embodiments of the invention are described below with reference to the drawings, which serve merely for illustration and are to be understood as non-restrictive. In the drawing,

[0084] FIG. 1 shows a fuel line in a sectional view perpendicular to the running direction, and

[0085] FIG. 2 shows another example of a fuel line 1′ of the invention in a section perpendicular to the main running direction; this fuel line has five layers: outside of the external layer 4 there is a further external layer 8 and an outermost layer 9, wherein the structure of the innermost fluoropolymer layer (3) and of the directly adjoining polyamide layer (4) is as described above; most importantly, the structure has the particular adhesion between the layers 3 and 4.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0086] FIG. 1 shows an example of a fuel line 1 of the invention in a section perpendicular to the main running direction. The line is in particular intended for fuels for vehicles, specifically gasoline or diesel. The line is preferably for gasoline, i.e. a hydrocarbon mixture. Main constituents of the gasoline are primarily alkanes, alkenes, cycloalkanes and aromatic hydrocarbons having 5 to 11 carbon atoms per molecule and a boiling range between 25° C. and about 210° C. Alongside these, various ethers (such as MTBE, ETBE) and alcohols (ethanol and optionally methanol) can be admixed with the unmodified gasoline. The ethers and/or the ethanol increase the knocking resistance of the gasoline. The cross-sectional area here can be constant along the main running direction, i.e. the shape of the pipe can in essence be hollow-cylindrical.

[0087] However, the cross-sectional area can also vary along the main running direction, for example in the form of a corrugated pipe.

[0088] The pipe wall encloses an internal space 2. The internal space 2 is followed radially outward firstly by an internal layer 3, the internal surface 7 of which adjoins the internal space 2 and delimits same. The configuration of this internal layer is based on a fluoropolymer.

[0089] Directly adjoining the internal layer 3, with no adhesion-promoter layer therebetween in the contact region 5, there follows an external layer 4, the configuration of which is based on polyamide 616, preferably without further constituents consisting of other polyamides. The external surface 6 of the external layer 4 delimits the line externally.

[0090] Starting Materials Used:

[0091] External Layer:

[0092] PA 12: polyamide 12: η.sub.rel=2.2 (m-cresol); T.sub.m measured by DSC in accordance with ISO 11357 (2011)=173° C., obtainable with trademark Grilamid L 25 W 40 X, EMS-CHEMIE AG, Switzerland.

[0093] PA 612: polyamide 612: η.sub.rel=2.3 (m-cresol); T.sub.m measured by DSC in accordance with ISO 11357 (2011)=218° C., plasticized and impact modified, obtainable with trademark Grilamid 21) 25 W 20 X, EMS-CHEMIE AG, Switzerland.

[0094] PA 616: polyamide 616: η.sub.rel=2.2 (m-cresol); T.sub.m measured by DSC in accordance with ISO 11357 (2011)=197° C., plasticized and impact modified.

TABLE-US-00001 TABLE 1 Composition of PA 616 Polyamide 616 (η.sub.rel = 2.2) % by weight 85.7 Plasticizer % by weight 8.0 Impact modifier % by weight 5.0 Hostanox O 3 P % by weight 0.5 Sandosab P-EPQ % by weight 0.2 Hostavin N 30 P % by weight 0.3 Tinuvin 234 % by weight 0.2 Magnesium stearate % by weight 0.1 Polyamide 616 (η.sub.rel = 2.1) % by weight 62.7 Impact modifier % by weight 10.0 Hostanox O 3 P % by weight 0.3 Carbon black % by weight 27.0 PA 616-ESD: polyamide 616: η.sub.rel = 2.1 (m-cresol); T.sub.m measured by DSC in accordance with ISO 11357 (2011) = 197° C., impact-modified and comprising carbon black. PA 12-HV: adhesion (elastomer)- and impact-modified polyamide 12: obtainable as Grilamid XE 4076 from EMS-CHEMIE AG, Switzerland. PA 6: heat-stabilized, impact-modified and plasticized polyamide 6, obtainable as Grilon BRZ 347 W from EMS-CHEMIE AG, Switzerland. BBSA (N-butylbenzenesulfonamide) was used as plasticizer (P). This is obtainable with trademark Uniplex 214 from Lanxess.

[0095] Impact modifier: acid-modified ethylene/α-olefin copolymers were used as impact modifier (IM), specifically maleic-anhydride-grafted ethylene-butylene copolymers and maleic-anhydride-grafted ethylene-propylene copolymers, and also mixtures of these.

[0096] IM system used: MVR value (measured at 230° C. with 2.16 kg) of 1.3 g/10 min (ASTM D1238), DSC glass transition temperature in accordance with ISO standard 11357-2 (2013) of −60° C., obtainable as Tafmer MC201 from Mitsui Chemicals.

[0097] Stabilizers: Hostanox O 3P is a stabilizer based on a hindered phenol with CAS No. 32509-66-3, Sandosab P-EPQ is a diphosphonite stabilizer (CAS: 119345-01-6), and Hostavin N 30 P is a stabilizer based on a hindered amine (HALS) with CAS No. 202483-55-4, all obtainable from Clariant.

[0098] Tinuvin 234 is a UV stabilizer based on benzotriazole with CAS No. 70321-86-7, obtainable from BASF SE. Magnesium stearate, purchased from Bärlocher GmbH, Munich, was used as lubricant.

[0099] Carbon black: carbon black with trademark ENSACO 250 Granules from Imerys was used as conductivity additive.

[0100] Internal Layer:

[0101] Fluoropolymer: material used for the internal layer was either a fluoropolymer based on ethylene and tetrafluoroethylene units (GTFE) or a fluoropolymer based on ethylene, hexafluoropropene and tetrafluoroethylene units (EFEP).

[0102] ETFE in the working examples was a product from AGC Chemicals Europe, Ltd., obtainable with trademark FLIJON® ETFE. ETFE-ESD in the working examples was a product ETFE AH 600-C, likewise from AGC Chemicals Europe, Ltd.

[0103] EFEP used was the commercially available product Neoflon EFEP RP-5000 from Daikin Industries, Ltd., Japan.

[0104] Production of the Test Specimens:

[0105] Pipes were coextruded in a Nokia Maillefer COEX5 pipe extruder at melt temperatures of 275-285° C. (fluoropolymer) and 240-255° C. (polyamide) at reduced pressure of 27 to 95 mbar and an extrusion speed of 12.9 m/min. Pipes with an external diameter of 8 mm and wall thickness of 1 mm were used as test specimens. The length of the pipe was adjusted as required by the tests. The thickness of the internal layer was 0.1 or 0.2 mm, and that of the external layer and, respectively, the further external layers was 0.9 and, respectively, 0.8 mm.

[0106] Tests Carried Out on the Pipe Structures:

[0107] Leaching: Test in accordance with SAE J2260 with test fuel FAM-B (in accordance with SAE J1681 (2000))=96-hour test, closed 200 cm pipe at 60° C.; maximal extract on the basis of VW TL 52712-C 6 g/mW (this standard determines ETFE-PA 12 requirements for 0.2 mm ETFE/0.8 mm PA 12).

[0108] Low-temperature performance: is tested on the basis of TL 52712-C in accordance with VW standard PV 3905. The drop height of the sphere is 65 cm. At least 10 test samples are tested and the number of fractures is stated in percent.

[0109] Pipe tensile test: Pipe tensile tests were carried out in accordance with ISO 527-2 (2012). Tests used test specimens of length 150 mm (tensile tests in extrusion direction) or 10 mm (in the case of tensile tests perpendicular to the extrusion direction). The test temperature was 23° C. and the test velocity was 100 mm/min (for tests in extrusion direction) or 25 mm/min if tests were carried out perpendicular to the extrusion direction.

[0110] Tests carried out in accordance with ISO 527 were specifically the following: tensile strain at break in extrusion direction, tensile strain at break perpendicular to the extrusion direction, yield stress in extrusion direction and yield stress perpendicular to the extrusion direction.

[0111] Bursting pressure/Comparative stress: in accordance with DIN 73378 at 23° C.

[0112] Layer adhesion: was tested in accordance with VW TL 52712 paragraph 6.8 and in accordance with SAE 72260.

[0113] Relative viscosity: DIN EN ISO 307 (2007), in 0.5% by weight m-cresol solution or 1% by weight sulfuric acid solution at a temperature of 20° C.

[0114] Zinc chloride resistance: test specimens were subjected to a period of immersion in accordance with SAE J2260, section 7.12.2, and then visually assessed for cracks. Test samples that were still intact were then subjected to the pendulum impact test and bursting pressure test in accordance with DIN 73378. Pendulum impact values, reported as percentages, relate to the proportion of tests not passed.

TABLE-US-00002 TABLE 2 Compositions and structure Structure/Description IE1 IE2 IE3 CE1 CE2 CE3 Interior layer EFEP EFEP ETFE EFEP EFEP EFEP Layer thickness mm 0.2 0.1 0.1 0.1 0.1 0.1 Exterior layer PA 616 PA 616 PA 616 PA 12 PA 612 PA 12-HV Layer thickness mm 0.8 0.9 0.9 0.9 0.9 0.9 Properties Tensile strain at % 358 351 361 358 364 320 break in extrusion direction Tensile strain at % 385 256 251 221 232 210 break perpendicular to extrusion direction Low-temperature 0 0 0 0 0 0 impact resistance (−40° C., 880 g) Leaching resistance g/mm.sup.2 1.85 3.6 1.22 5.4 5.3 5.7 (soluble constituents) Leaching resistance g/mm.sup.2 0.1 0.1 0.1 0.1 0.1 0.1 (insoluble constituents) Comparative stress in N/mm.sup.2 27 28 29 23 25 23 new condition at 23° C. Comparative stress in N/mm.sup.2 10 10 11 6 6 6 new condition at 115° C. Comparative stress N/mm.sup.2 26.6 27 29.7 18 19 18 after immersion in FAM-B for 500 h at 23° C. Comparative stress N/mm.sup.2 10 10.5 11.2 4.7 5.1 4.8 after immersion in FAM-B for 500 h at 115° C. Change of comparative % −1.5 −2.1 2.4 −22 −24 −22 stress after immersion in FAM-B for 500 h at 23° C. Change of comparative % 0 −4.5 1.8 −22 −24 −22 stress after immersion in FAM-B for 500 h at 115° C. Adhesion not not not separable separable separable separable separable separable Zinc chloride resistance Cracks none none none none cracks cracks Pendulum impact % 0 0 0 20 n.d. n.d. Bursting pressure bar 77 79 81 66 n.d. n.d. n.d.: not determined because of visual assessment

TABLE-US-00003 TABLE 3 Compositions of three-, four- and five-layer structures Structure/Description IE4 IE5 IE6 CE4 CE5 Number of layers 3 3 5 4 4 Layer 1 from inside ETFE-ESD ETFE ETFE ETFE ETFE to outside Layer thickness (mm) 0.1 0.1 0.1 0.1 0.1 Layer 2 from inside PA 616-ESD PA 616 PA 616 PA 612 PA 612 to outside Layer thickness (mm) 0.1 0.1 0.1 0.1 0.1 Layer 3 from inside PA 616 PA 612 PA 612 PA 6 PA 6 to outside Layer thickness (mm) 0.8 0.8 0.1 0.4 0.4 Layer 4 from inside — — PA 6 PA 616 PA 612 to outside Layer thickness (mm) — — 0.4 0.4 0.4 Layer 5 from inside — — PA 612 — — to outside Layer thickness (mm) — — 0.3 — — Properties Tensile strain at % 340 300 250 200 200 break in extrusion direction Tensile strain at % 250 200 180 130 130 break perpendicular to extrusion directicn Low-temperature 0% 0% 0% 20% 20% impact resistance (−40° C., 880 g) Leaching resistance g/mm.sup.2 1.2 1.2 1.5 3 3 (soluble constituents) Leaching resistance g/mm.sup.2 0 0 0 0 0 (insoluble constituents) Comparative stress in N/mm.sup.2 27 27 27 27 27 new condition at 23° C. Comparative stress in N/mm.sup.2 10 10 10 10 10 new condition at 115° C. Comparative stress N/mm.sup.2 28 28 28 19 19 after immersion in FAM-B for 500 h at 23° C. Comparative stress N/mm.sup.2 10.5 10.5 10.5 7 7 after immersion in FAM-B for 500 h at 115° C. Change of comparative % 3.7 3.7 3.7 −30 −30 stress after immersion in FAM-B for 500 h at 23° C. Change of comparative % 5 5 5 −30 −30 stress after immersion in FAM-B for 500 h at 115° C. Adhesion not not not separable separable separable separable separable separable Zine chloride resistance Cracks none none none cracks cracks Pendulum impact % 0 0 0 n.d. n.d. Bursting pressure bar 80 80 80 n.d. n.d.

[0115] Discussion of Results

[0116] The inventive examples are particularly characterized by their excellent layer adhesion. Analogous aliphatic AABB polymers, i.e. polyamides, consisting of a diamine and of a diacid, surprisingly exhibit different adhesion to the fluoropolymer layer. Polyamide 616, with an average number of 11 carbon atoms (11C) has significantly better adhesion to the fluoropolymer than the long-chain systems such as PA 12 (12C) or PA 612 (9C), which the person skilled in the art knows to be analogous.

[0117] Surprisingly, the inventive examples exhibit excellent pressure properties after a period of immersion in a fuel. The comparative stress of the structures according to the claims undergoes only slight decrease after an immersion time of 500 hours in FAM-B. The high zinc-chloride resistance permits problem-free use of the inventive lines in the automobile sector. Such lines exhibit no cracks after a period of immersion in a ZnCl.sub.2 solution, and moreover have mechanical properties that are more advantageous than those of known structures based on PA 12 or PA 612.

LIST OF REFERENCE SIGNS

[0118] 1 Fuel line [0119] 2 Internal space [0120] 3 Internal layer [0121] 4 External layer [0122] 5 Contact region between 3 and 4 [0123] 6 External surface [0124] 7 Internal surface [0125] 8 Further external layer [0126] 9 Outermost layer